Tree Facts: Recognizing and preventing hazardous trees

Farm Forum

We are responsible for the safety of people and property in the vicinity of the trees we own. In public places such as a park, the unit of government that owns and operates it is responsible. Property damage, injury and even death may happen because of a defective tree.

Trees should be inspected on a regular basis in order to recognize situations that might cause them to break or fall. Start with a good set of binoculars for the tops of tall trees, then look downward along the trunk and then examine the root zone. A hazardous tree has a structural defect that may cause the tree or a portion of it to fall on someone or something of value. A non-hazardous tree can be healthy and sound or dead or dying in a remote field away from paths and people.

• Examine The Top And Crown – When doing your tree inspections look for large dead limbs, loggers call these widow-makers. Dead limbs are an accident waiting to happen and can fall from wind or a child climbing up a tree. If a tree has been topped in the past there will be many weakly attached limbs from where it was cut. Remove any of these branches that might be a problem. Prune off any branches that cross or rub as they lead to weakened branches that may break. Assess the vigor of the tree by looking for the amount of leaf cover and leaf size. Do this by comparing the tree to other trees of the same type. Dead or dying trees around structures and paths promptly removed. If the same type of trees are in remote areas leave them for wildlife.

• Check The Trunk – Watch for and or prevent forked trunks as the crotches are weak. If possible remove one side of the fork when the tree is young. Many times they become decayed. Examine wounds and cracks and other openings for decay. Lightning scars that extend into the ground are of particular concern. If you find two vertical cracks on opposite sides of the trunk it can be a sign of root rot injury or breakage. Look for signs of decay of the trunk or large branches indicated by cavities or cankers and fruiting bodies of fungi called cankers.

• Don’t Forget The Roots – Diseased or damaged structural roots can cause trees to become hazardous. Look for mushrooms on or near the base of the tree as they are a bad sign of root problems. Feeder roots may continue functioning giving the tree a healthy appearance while decay continues in the structural roots until the tree falls over. Trenching or construction around trees can cause structural roots to be unbalanced subject to wind throw. The severed roots also are wounded and decay organisms move in with associated fungi making trees hazardous.

There are other tree hazards that can cause damage to property and injuries to people. Heavy fruit or nut production on some trees can fall down. Trees with thorns such as locust and Russian Olives can be dangerous especially to children, cause scratches to equipment and flat tires. Also, trees grown up into power lines can cause interruptions in electrical service and electrocution dangers.

My source for this news release was the Arbor Day Foundation. If you would like more information about “Recognizing and Preventing Hazardous Trees,” contact Bob Drown at the Conservation Office at 605-244-5222, Extension 4 or by e-mail at